In connection with the celebration of the 200-year anniversary of the Swedish throne Bernadotte's going ashore in Sweden and entry into the Swedish royal family, there will be events associated with the celebration of urban Elsinore and Helsingborg on 20 October 2010.

I'd be surprised if any royals from other houses attended. The best guide prior to the event would be to look at the 2005 Bernadotte Family Reunion, which was attended by the Swedes, the Danes and I think Queen Anne-Marie with some of her family. I'd venture to say that Queen Margrethe and Princess Benedikte are only attending the anniversary because they are close relations to the Swedes through their mother, the former Princess Ingrid of Sweden (a Bernadotte).

Here's a link to the full program of tomorrow's festivities celebrating the day the new Bernadotte Crown Prince set foot on Swedish soil for the first time, 200 years ago.
Attended by The Swedish King and Queen, the CP couple and Prince Carl Philip, as well as Queen Margrethe and Princess Benedikte of Denmark, the events take place all day, starting in Helsingör/Denmark and continuing in Helsingborg/Sweden: